Russian and Ukrainian delegates met in Istanbul on Monday for their second set of direct peace talks, a day after Kyiv launched a shock drone attack on Russia’s nuclear-capable bombers, in an operation that President Volodymyr Zelensky said was a year and a half in the making.

Ukraine’s security service released footage Wednesday of its attack on Russian war planes at multiple airbases across the country. In the span of a few hours on Sunday, nearly a third of Moscow’s strategic bomber fleet was destroyed or damaged with cheaply made drones sneaked into Russian territory, according to Ukrainian officials.

Delegations from Russia and Ukraine are in Turkey for their second round of direct peace talks in just over two weeks.